321.93 Defense.

Under a charge of possessing a vehicle or component part, the vehicle identification
number or component part number of which is defaced, altered, or tampered
with, it shall be a complete defense that the accused at the time of such
possession had in the accused's possession a certificate of title from the
officer whose duty it is to register vehicles and component parts in the
state in which the vehicle or component part is registered, showing good
and sufficient reason why numbers are defaced, changed, or tampered with,
the original vehicle identification number or component part number, and
the ownership of the vehicle or component part.